Coatings including tobacco products as corrosion inhibitors

Abstract

The invention relates to coatings, such as paints, containing tobacco products and the use thereof as corrosion inhibitors. The tobacco products include various forms of tobacco such as dried tobacco leaves, stems, dust, liquid extracts, etc, that can be added to the coatings. The invention further relates to treatment methods and compositions for surface treatments such as descaling, pickling and removing surface deposits and corrosion products.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 60 / 940,743, filed May 30, 2007, which application is expressly incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to coatings, such as paints, containing tobacco products and the use thereof as corrosion inhibitors. The tobacco products include various forms of tobacco such as dried tobacco leaves, stems, dust, liquid extracts, etc, that can be added to the coatings. The invention further relates to treatment methods and compositions for surface treatments such as descaling, pickling and removing surface deposits and corrosion products.[0004]2. Related Art[0005]The simplest and most widely used protective system for metals against corrosion is painting and a very wide variety of protective paints are available to industry. For many years the commonly used prot...

AI Technical Summary

Benefits of technology

[0019]Salt fog chamber data indicate that additions of tobacco dust and liquid tobacco extracts provided excellent corrosion protection to the 2024 substrate and, further, had no deleterious effects on the stability of the coating. It was concluded that tobacco dust additions should be limited to approximately 5 wt. % and liquid extract additions to 10 wt. % to ensure optimum coating performance when Deft 44GN098 Chrome-free water reducible epoxy primer (as supplied) is used as the primer. Different addition levels are clearly possible in coatings formulated without inhibitive pigments.

[0020]These results show that in coatings that perform well; tobacco additions to the coating provided excellent corrosion inhibition over a 3 month test period. In cases where the coatings contained defects, and so can be expected to fail in a relatively short test period, the tobacco additive (particulate dust in this study) appeared to slow the corrosion damage to the substrate. The findings suggest that even when defects are present in the coating and allow the rapid ingress of moisture to the coating / substrate interface, the presence of solid tobacco particles in the coating plays a role in slowing the corrosion rate overall and possibly also blocks particular reactions all together.

[0021]The findings of this study indicate that tobacco additions to primer coatings, both as dust and as liquid tobacco extracts, provide corrosion protection to the 2024 substrate. Further, there are indications that the presence of tobacco may change the nature of the corrosion reactions. Pilot potentiostatic polarization studies indicate that both the cathodic and the anodic reactions are polarized by the presence of tobacco in solution. These reaction polarization effects result in a shift of the corrosion potential to more noble values and reduced cathodic and anodic current densities compared to bare aluminum in 3.5% NaCl.

[0022]Overall, this study demonstrates the effectiveness of tobacco in inhibiting the corrosion of 2024 aluminum alone and when coupled to silver, the latter situation being found with conductive coatings.

[0023]Additionally, while tobacco in its various forms (e.g., leaf, dust, extracts, etc.) is a highly effective corrosion inhibitor for latex and oil paints and for pickling acids and both acidic and alkaline cleaning media, it can also be combined with other inorganic (e.g., chromates, nitrites, phosphates and silicates), metallic and metal oxide, and organic (e.g., benzoates, amines) pigments to take advantage of synergistic effects when two or more inhibitive pigments are combined into a formulation. Further, by combining two or more inhibitive pigments into a formulation, it is further possible to take advantage of changes in the addition level requirements in paint formulations, particularly when synergistic effects are present. Among other things, for example, tobacco additions markedly improved the corrosion inhibition of steel rebar by the standard concrete additive DCI, and is a good example of inhibition synergistic effects

Problems solved by technology

One problem with these acids used for descaling is that they tend to promote corrosion of metal pipes and structures, especially when dissimilar metals are coupled together.

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